Intervertebral fusion may be performed to treat degenerative disc disease, spinal disc herniation, discogenic pain, spinal tumor, vertebral fracture, scoliosis, lordosis, kyphosis, spondylolisthesis, spondylosis, other degenerative spinal conditions, or any condition that causes instability of the spine. In some fusion procedures, an intervertebral implant such as a spacer or cage is placed between the vertebral bodies to provide stability. Bone graft material may be placed in the implant to promote fusion of the adjacent vertebrae.
Access to the intervertebral space between two vertebral bodies may be obtained through posterior, anterior or lateral surgical approaches. A true lateral approach requires passing through the psoas muscle to reach the intervertebral disc space. In order to minimize trauma to the muscle and the nerves in its vicinity, it may be preferable to shift the lateral trajectory anteriorly to access the anterior third of the disc space. Need exists for an implant which may be inserted from a lateral approach into the anterior portion of the disc space and expanded asymmetrically to fill the disc space.